Method of extracting precious metals from their ores.



' T. I3. CROWE.

ING PRECIOUS METALS FROM THEIR GRES.

APPLICAHON FILED MAR.21915.

METHOD 0F EXTRACT I @im ifg NMI

THOMAS B. CROWE, OF VICTOR, COLORADO. ASSIGNOR TO I'I-IE PORTLAND GOLD MINING COMPANY, OF COLORADO SPRINGS, COLORADO, A CORPORATION OF WYOMING.

METHOD OF EXTRACTING PRFOIOUS METALS FROM THEIR CRES.

Littllll.

Application filed March 2, 1915.

To (1U Hmm 'it 11mg/ conce/rn.'

Be it known that I, Tilonms B. Crown, a citizen of the United States, residing at Victor, in Teller county, in the State of Colorado, have invented certain new and useful Improvements in Methods of Extracting Precious Metals from Their Orcs, of which the following is a specification.

his invention relates to the extraction of precious metals from their ores and particularly to extraction by the so-called cyanid method, although the invention is not limited to the use ot' any particular solvent.

Heretofore it has been customary in a socalled cyanid process to cause the dissolution of the precious metal in the cyanid solution by agitating finely ground ore in contact with the solution. This method of dissolving the precious metals from -the ores, as heretofore practised, is very slow and consequently involves considerable expense, as a continual application of power is necessary to cause agitation.

I have discovered that the rate of dissolution of the precious metals in hydrometallurgical processes is approximately proportionally to the pressure which is applied to the mixture. As a result of this discovery, I have devised a new process which consists essentially of applying a pressure greater than atmospheric pressure to the mixture of solvent solution and ground ore during the agitation of the same. By this method, I am enabled greatly to accelerate the dissolution of the precious metals and thereby accomplish the dissolution at much less cost than has heretofore been practicable.

In order that my new method may be clearly understood, I will describe a particular forni of it in connection with the accompanying diagram illustrating an apparatus in which it may be conducted. It

should be clearly understood, however, that my invention is by no means limited to the particular method illustrated and described. The accompanying drawing illustrates diagrammatically an apparatus in which agitation of the ground ore and solvent solution may be accomplished.

The apparatus illustrated is in part similar to the well-known Pachuca agitator. It differs, however, from the Pachuca agitator in having an air-tight top or cap l, in which Specification of Letters Patent.

Patented dept. I2, IIG.

serial No. 11,603.

is an air outlet pipe Q, controlled bv a valve- 3. `Within the tank l is the barrel or pipe 5, open at both ends, such as is customarily found in Pachuca agitators. Compressed air is admitted to the bottom oi this barrel through the pipe (i.

In conducting my new process the ore is first ground or` comminuted by any ordinary method. The ground ore and solvent, colisisting of' a solution of c vauid of potassium or c vanid of sodium is placed in the agitator tank -l through the usual inlets which are not shown in the diagram. The tank is filled to the level indicated in the diagram by the line 7. Compressed air is then! admitted through the pipe (S to cause the circulation and agitation ot the mixture. The valve 3 is kept closed until the desired pressure for the dissolution is reached. The degree of pressure which can be used is determined by the strength of the tank and other practical considerations. The greater the pressure used the more rapid the dissolution. lVhen the pressure, which is indicated by the gage 8, has reached the point desired in the particular apparatus, the valve 3 is opened sufficiently to maintain the pressure constantly at this point. A stable condition is thus obtained in which compressed air is continuously forced in through the pipe rises through the barrel 5, causing agitation of' the mixture and escapes through the valve 3 into the atmosphere at such rate that a pressure greater than atmospheric is constantly maintained within the tank.

My invention is by no means limited to use in connection with the particular type of agitator described but may be used in connection with any method of' agitation whether or not the agitation is caused by compressed air.

I claim as my invention 1. A method of extracting precious metals from their ores, which consists in placing finely groimd ore in a cyanid solution, blowing into the mixture under pressure a constantly' renewed supply of fresh atmospheric air, while maintaining the mixture under a pressure greater than atmospheric pressure.

Q. A method of extracting precious metals from their ores, which consists in placing finely ground ore in a cyanid solution. blowing a constantly renewed supply oi fresh atmospheric air into a mixture, and restricting the escape of said air, so that the miX- sure greater than atmospheric pressure upon ture is maintained under pressure greater the mixture. 10 than the atmosphere. In testimony whereof, I have hereunto 3. A method of extracting precious metals signed my name in the presence of Witnesses.

5 from their ores, which consists in placing THOS. B. CROWE.

finely ground ore in a cyanid solution, bloW- Witnesses: ing 'into the lmixture a constantly renewed W. R. WooDs, supply of oxygen, While maintaining a pres- GLADYS OLVER. 

